From: ahoward <ahoward@...>
Date: 2003-05-30T06:43:59+09:00
Subject: Re: Metakit for Ruby - Would you want it?

On Thu, 29 May 2003, Anders Borch wrote:

> Brian Candler wrote:
> > On Fri, May 30, 2003 at 04:02:07AM +0900, Anders Borch wrote:
> >
> >>what I would like is an embedded sql database. It seems to me that
> >>metakit does not have an sql parser. having an sql parser would let me
> >>make a dbi interface and use an embedded database w/o changing a single
> >>line of code.
> >
> >
> > You mean like sqlite? http://www.sqlite.com/
>
> yeah! exactly like sqlite! you just saved my day :)
>
> > There are ruby bindings which work more or less (get the latest ruby-dbi-all
> > from CVS)
>
> and it even has a DBI interface! this is *so* cool! :D

i had problems with the api - if the api returned an error code the connection
went stale and all sorts of trouble ensued... eg.

  #!/usr/bin/env ruby
  require 'sqlite'

  db = SQLite.new('bar.db')

  sql = "create table bar (answer int);"
  db.exec (sql)

  sql = "insert into bar values (42);"
  #sql = "insert into foobar values (42);"  # ERROR
  db.exec (sql)

  query = "select * from bar;"
  tuples = db.exec (query)

when run produces

  [answer]
  42

but if you use the line marked 'ERROR' instead it gives

  bar.rb:7:in `exec': method call on terminated object (NotImplementedError)
          from bar.rb:7

> sadly sql isn't standardized at all (in practice), but that does not
> change the fact that everyone and their mothers speak some subset of
> sql. Therefore if anyone but me is going to maintain and develop for
> systems that I made, then I need to use stuff they know - like sql in
> stead of some odd db interface... also half of the time i'm building
> software using ruby and storing data in some sql database and someone
> else is writing some other software in java that works with the same
> data. If I am to work together with other people across languages it's
> often better to have a common ground that is an sql database.
>
> > If you just want objects which persist, and your database isn't so enormous,
> > you might like to take a completely different approach (e.g. madeleine)
>
> yeah, I have been looking at a some of those solutions... db-backend was
> the one I was most impressed with. It was also the one most likely to
> fulfill my needs. I would like to have a nice database backend stucture
> (as made possible in db-backend) combined with ease of use (as in some
> of the non-sql variants out there).
>
> db-backend makes it possible to have a nice database structure but the
> price is that I need to define the database to ruby object mappings.
> madeleine (and the like - i looked at a couple of those) lets me easily
> have persistent objects but I cannot easily interact with the java
> people whom I would like to share my objects with.
>
> So, in the spirit of so many other open source developers, I did not
> expand upon existing code, but in stead I started my own project. I aim
> to have easily persisten objects and at the same time have an easily
> manageable database structure.
>
> The project is awailable at http://rsqlserial.sf.net (and at RAA -
> search for sql and it should be among the top 10 hits).
>
> I ended up rather off-topic and with a not very subtle plug for my own
> (still alpha) project. But hey - I got my sqlite now!
>
> In an effort to get back on topic: more embedded databases can only
> benefit us all. And for those who - like Brian - do not like sql,
> metakit looks very nice indeed. From what I read of the API it seems
> very nice and sleek. Go ahead and make a ruby binding for it :)

very well put - and totally correct IMHO.  i will check out your project.

-a
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  | Ara Howard
  | NOAA Forecast Systems Laboratory
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